The references cited throughout the present application are not admitted to be prior art to the claimed invention.
Anthrax is a bacterial infection produced by Bacillus anthracis. Bacillus anthracis endospores can enter the body through skin abrasions, inhalation, or ingestion. Bacillus anthracis produces an anthrax toxin that is often lethal. (Dixon et al., (1999) N. Engl. J. Med. 341, 815-26.)
Anthrax toxin consists of three proteins, a receptor-binding component designated protective antigen, and two enzymatic components termed edema factor and lethal factor (“LF”). (Mock et al., (2001) Annu. Rev. Microbiol. 55, 647-71.) Lethal factor is a zinc-dependent metalloprotease that appears to exert toxic affects by cleaving mitogen-activated protein kinase kinases (MKKs). (Vitale et al., (1998) Biochem. Biophys. Res. Commun. 248, 706-11, Vitale et al., (2000) Biochem. J. 352 Pt 3, 739-45, Duesbery et al., (1998) Science 280, 734-7, Duesbery et al., International Publication No. WO 99/50439, International Publication Date Oct. 7, 1999.)
Vitale and co-workers have used microsequencing to identify the site in different MKKs that are cleaved by lethal factor. (See Table 1, Vitale et al., (2000) Biochem. J. 352 Pt 3, 739-45.) Lethal factor cleavage of different MKKs occurred within the N-terminal region preceding the kinase domain. Alignment of the sequences flanking the cleavage site revealed some consensus motifs: a hydrophobic residue in position P2 and P1′, and at least one basic residue between P4 and P7. (Vitale et al., (2000) Biochem. J. 352 Pt 3, 739-45.)
Lethal factor has been indicated to cleave synthetic peptides in vitro. (Hammond et al., (1998) Infect. Immun. 66, 2374-8.) In vitro cleavage was inhibited by 1,10-phenanthroline or 10 mM EDTA, both of which chelate zinc.
Bacillus anthracis is a spore forming gram-positive bacillus, which is the etiologic agent of anthrax. Anthrax is a disease that can be found globally in temperate zones (e.g. South and Central America, South and East Europe, Asia, Africa, Middle East, and Caribbean) and is transmissible to humans through handling or consumption of contaminated animal products (e.g. eating undercooked meat from infected animals). Wildlife mammals such as deer, wildebeest, elephants, and domesticated livestock, such as goats, sheep, cattle, horses, and swine are at high risk for contracting the disease. Contraction generally occurs from grazing on contaminated land, eating contaminated feed or drinking from contaminated water holes. Bacillus anthracis spores can remain viable in soil for many years. See Helgason et al., Applied and Environmental Microbiology 2000 66(6) pgs. 2627-2630; Wber et al., Antimicrob Agents and Chemotherapy 1988 32(5): 642-645; and Doganay et al., Scand. J. Inf. Dis. 1991 23:333-335 for further discussion of Bacillus anthracis. 
In humans three forms of anthrax infections can occur, cutaneous, gastro-intestinal and inhalational. With the cutaneous form, infections occur when the bacterium or spore enters a cut or abrasion on the skin. See Synder, J. W., Shapiro, D. S., Gilchrist, M. J. R., et al., “Basic Diagnostic Testing Protocols for Level A Laboratories (For The Presumptive Indentification of Bacillus anthracis)” at www.ban.asm.1a.cp.102401f, Oct. 24, 2001, pgs. 1-20 and Dixon, et al., NEJM 341: 815-826 Sep. 9, 1999 Number 11. Symptoms of the skin infection are generally raised itchy bumps or bump that resembles an insect bite. Within one to two days, the bumps or bump develops into a fluid-filled vesicle, which ruptures to form a painless ulcer with a characteristic black necrotic (dying) area in the center. If left untreated, death can result, however, deaths are rare if appropriate antibiotic therapy is administered.
Gastrointestinal anthrax generally occurs from the consumption of meat contaminated with the bacterium, which results in an acute inflammation of the intestinal tract. Signs of nausea, loss of appetite, vomiting, fever, along with abdominal pain, vomiting of blood and severe diarrhea are indicative of gastrointestinal anthrax. The mortality rate for this form of human anthrax is estimated at 25%-60%.
Inhalation anthrax is most likely the result of intentional aerosol release of Bacillus anthracis, such as an act of bioterrorism. This form of human anthrax infection commonly has an incubation period of one to six days, with fever, malaise, fatigue, a nonproductive cough and/or mild chest discomfort sometimes being the initial signals. These initial symptoms are often followed by a short period of improvement, followed by the abrupt development of sever respiratory distress with labored breathing, perspiration and bluish skin color. Death usually occurs within 24-36 hours after the onset of respiratory distress despite aggressive treatment.
Most Bacillus anthracis strains are sensitive to a broad range of antibiotics. The commonly prescribed therapies today are ciprofloxacin, penicillin, or doxycycline. However, the efficacy and side effect profiles of these agents are not ideal.
While antibiotics can kill the bacteria that cause anthrax, the tripartite anthrax toxin continues to damage the body even when the bacteria themselves are dead. Therefore, there still exist the need for new and effective therapies with improved efficacy, little or no side effect and which inhibit the scissor-like ability of lethal factor to snip apart imprtant host molecules.